Underwater drilling and production vessel

ABSTRACT

An elongated housing having a fluid tank extending about its axis is divided into a plurality of housing chamber portions by decks extending therethrough, is maintained in a substantially vertical position spaced preselected distances from the top and bottom surfaces of a body of water and has a conduit extending from the chamber of the vessel upwardly to a position above the top surface of the water.

United States Patent Clark 51 Jan. 9, 1973 541 UNDERWATER DRILLING AND 2,908,141 10 1959 Marsh ..114/.5 D PRODUCTION VESSEL 3,372,745 3/1968 Holmes ..l66/.6 3,456,720 7/1969 Brewer.... 1.l66/.5 [75] lnventor: Ernest E. Clark, Bartlesvllle, Okla. 3,470,838 10/1969 Danienflfl "114/5 Assignee: Petroleum p y Howard X [22] Filed: Oct. 5, 1970 Primary ExaminerMarvin A. Champion Assistant Examiner--Richard E. Fa'vreau [21] Appl 78118 Attorney-Young and Quigg [52] US. Cl ..175/8, 114/5 [57] ABSTRACT [5]] Int. Cl. ..E2lb 15/02 An elongated housing having a flu1d tank extending [58] Flew of Search iz 2f about its axis is divided into a plurality of housing chamber portions by decks extending therethrough, is maintained in a substantially vertical position spaced [56] References cued preselected distances from the top and bottom sur- UNITED STATES PATENTS faces of a body of water and has a conduit extending from the chamber of the vessel upwardly to a pos1t10n 3,080,583 3/1963 Fuller ..1 14/5 D above the top surface of the water. 3,556,210 5/l969 Johnson 3,391,734 7/1968 Townsend ..l66/.5 12 Claims, 7 Drawing Figures II II II ll 1.1,

PATENTEUJAR 9191a 3.709.307

sum 1 or 4 INVENTOR. E. E. CLARK II II BY LL W W? FIG. ATTORNEYS PATENIEDJAN 9197a 3.709.307

sum 2 or 4 Ll L 861/ a 1B INVENTOR- E. E. CLARK ATTORNEYS PATENTEDJAN 9197a 3.709.307

SHEET 3 UF 4 INVENTOR. E E. CLARK BY *QW'W ATTORNEYS FIG. 4

PATENTEUJAN 9 I975 SHEET 0F 4 FIG. 5

FIG.- 6

INVENTOR. E. E. CLARK FIG. 7

UNDERWATER DRILLING AND PRODUCTION VESSEL In the offshore drilling of oil and gas wells, adverse weather conditions often become sufficiently severe to cause the termination of drilling and production operations. At other times, the high winds and waves damage the drilling and production equipment and necessitate expensive and time-consuming structural repairs.

It is therefore an object of this invention to provide a composite drilling and production vessel that can be positioned a sufficient distance beneath the surface of the water to avoid adverse weather conditions and eliminate the necessity of terminating drilling and production operations during severe storms. Another object is to provide a vessel of a unique configuration in which drilling and production equipment can be conveniently installed and operated.

Other aspects, objects, and advantages of the present invention will become apparent from a study of the disclosure, the appended claims, and the drawing.

The drawings are diagrammatic views in partial section showing the vessel and associated equipment of this invention. FIG. 1 shows the apparatus installed in a body of water for drilling and producing fluid from a subterranean formation, FIG. 2 shows an embodiment of the chamber of the vessel and associated drilling and production equipment, FIG. 3 shows a sectional view taken along line 33 of FIG. 2, and including the tank, FIG. 4 shows a sectional view taken along line 4-4 of FIG. 2, FIG. 5 shows another embodiment of the first end portion of the housing, FIG. 6 shows another embodiment of the access tube, and FIG. 7 shows another embodiment of the first end portion of the housing.

Referring to FIG. 1, an elongated housing 2 is maintained by anchoring means 4, such as cables and piling inserted within the earth, for example, submerged within a body of water 6 at a desired location relative to a subterranean formation at a position spaced preselected distances from the top and bottom surfaces 8,10 of the water 6. The housing 2 is also maintained by the anchoring means 4 at a substantially vertical attitude with a first end portion 12 of the housing 2 at a higher elevation than the second end portion 14 of said housing 2.

The housing 2 is of a generally cylindrical configuration and has a longitudinal axis and a chamber 16 extending therethrough. The second end portion 14 of the housing 2 has a plurality of openings 18 extending therethrough, each being substantially parallel to the axis and spaced about said axis an arcuate distance one from the other and a common radial distance from said axis. The first and second end portions 12,14 of the tank are preferably of convex configuration for providing a vessel that can withstand greater fluid pressure on the outer surface of the housing 2. The housing should be able to withstand a liquid pressure of at least 50 psi, preferably higher, in order to maintain the vessel a preferred depth beneath the top surface 8 of the water 6 substantially removed from wave action.

A fluid tank 20 is positioned about the outer periphery of the housing 2, preferably circumscribing the axis of the housing 2. The tank 20 has a chamber which also preferably circumscribes the axis of the housing 2 and is divided by walls 24 within the tank chamber 22 for dividing the tank 20 into a plurality of tank chamber portions 26,28,30 with at least a portion of said chamber portions 26,28,30 each circumscribing the outer periphery of the housing 2.

Although it is preferred that the tank 20 and at least a portion of the tank chamber portions 26,28, for example, preferably all of the chamber portions, circumscribe the outer periphery of the tank, it should be understood that the tank 20 and the chamber portions can be of other configurations. This preferred embodiment of the tank 20 and the tank chamber portions 26,28,30 allows the placement of fluid within the tank chamber portions without subjecting the housing 2 to moments of large magnitude by the fluid within the tank 2. In order to facilitate installation of the vessel at a desired location, it is also preferred that the tank 20 be attached to the housing 2 along the axis of the housing preselected distances from the first and second end portions 12,14 of the housing 2. These distances are dependent upon the placement and weight of the drilling and production equipment 32,34 within the housing 2. These preferred distances can be easily calculated by one skilled in the art for the reduction of strain and stress on the housing during installation, removal, and operational conditions of the vessel. The tank 20 can also be in contact with and directly attached to the housing 2 or spaced a common radial distance from said housing. It is preferred, however, that the tank 20 be spaced a common radial distance from the housing 2 in order to increase the stability of the housing 2 and provide additional storage. This additional storage is provided by attaching the tank 20 to the housing by first and second attaching rings 36,38 that are spaced one from the other for providing a circular chamber 40 about the housing 2. The annular edge 42 of each ring 36,38 is attached to the tank 20 and the other annular edge 44 of each ring 36,38 is attached to the housing in this preferred embodiment. The circular chamber 40 can also have a plurality of walls 46 extending therethrough for dividing said circular chamber 40 into a plurality of chamber portions 48,50. In FIG. 1, the attaching rings 36,38 are not shown circumscribing the housing 2 in order to simplify the drawing and communicate the fact that the tank 20 can be attached to the housing 2 in a multiplicity of different manners.

A plurality of conduits 52,54,56,58, for example, are each attached on one end to one of the chamber portions 26,28,30,48, or 50, for example, and the other end to the chamber 16 of the housing 2 for selectively passing fluid between one of the chamber portions and the chamber 16 of the housing 2.

An access conduit 60 is attached at a first end 62 to the housing 2 in communication with the housing chamber 16 and extends upwardly therefrom with a second end 64 positioned a distance above the top surface 8 of the water 6 for movement of personnel and equipment between the chamber 16 of the housing 2 and a location above the water 6. A helicopter landing deck 66 is preferably attached to the second end 64 of the access conduit 60 and an elevator 68 is associated with the second end 64 of the access conduit 60 with said elevator 68 being movable between a first position (shown) at which a platform 70 of the elevator is ad jacent the helicopter deck 66 and a second position (not shown) at which the platform is within the chamber 16 of the housing 2.

Referring to FIG. 2, the housing 2 has a plurality of decks 72,74,76 extending across the chamber 16 of the housing 2 substantially perpendicular to the axis of the housing 2 for separating the housing chamber 16 into a plurality of housing chamber portions 78,80,82,84. At least a portion of the decks 72,74, 76, here all of the decks, has a plurality of openings extending therethrough with each opening being coaxially aligned relative to one of the openings 18 through the second end portion 14 of the housing 2 for the passage of drilling and production conduit 88 through the various housing chamber portions 78,80,82,84.

At least one of the decks 72, for example, has an overlying rotatable deck 90 movably connected thereto for rotation of said rotatable deck 90 about the axis of the housing 2. The deck has an opening 92 extending therethrough that is coaxially alignable with the openings 86 in the decks 72,74,76. A power source 94, here shown as an individual electric motor, for example, is operably connected to a gear 96 which is meshed with a track that runs circumferentially about the deck 72 for rotating the rotatable deck 90 relative to its associated deck 72 and maintaining the opening 92 of the rotatable deck 90 coaxially aligned with one of the deck openings 86.

The rotatable deck 90 can be mounted within the housing chamber 16 by other means by, for example, a track that is fixed directly to the housing 2. It is preferred, however, that the rotatable deck 90 be mounted on one of the decks 72,74 or 76 in order to additionally support the sometimes heavy equipment that is carried on the rotatable deck 90.

In the preferred embodiment of the apparatus, drilling equipment 32 is mounted on the rotatable deck 90 in the chamber portion 78, production and fluid processing equipment 34 is mounted on the next lower deck 74 in the chamber portion 80, and well heads 98, mud conduits 100 and blowout preventers 102 are mounted on the next lower deck 76 in the chamber portion 82.

Where an automatic rig 104 is utilized, it is preferred that the various types of equipment be located as set forth above in order to provide for easier handling of heavy drilling equipment from the access conduit 60 into the drilling zone. With other types of drilling rigs, as shown in FIGS. and 7, a crown deck 106 and overlying crown rotatable deck 108, similar to rotatable deck 90, can be advantageously employed.

Where an automatic drilling rig is utilized, the rig derrick 110 is fixedly attached to the rotatable deck 90 about the rotatable deck opening 92 for intermittently passing pipe from the derrick 110 through each of the derrick openings 86, each of the housing openings 18 and against the earth at spaced-apart locations for drilling, completing, and working over a plurality of wells beneath the housing 2.

The preferred automatic rig has hoist cylinders 112 and a vertically movable drilling head 114. The drilling head 114 has an opening 116 for releasably mounting an end of a pipe 118 therein, rotating the pipe and passing fluid into the pipe 118 and moving the end of the pipe 118 between a first position (not shown) at which the pipe end is adjacent the rotatable deck 90 and a second position (shown) at which the pipe end is spaced a vertical distance from the deck 90. Automatic rigs and their operation are well known in the art.

An elongated pipe racking element 120 is pivotally mounted on a rotatable deck adjacent the derrick for movement between a first position (shown by broken lines in FIG. 4) at which clamps 122 of the element are coaxially aligned with the openings 92 in the rotatable deck 90 and a second position (shown in FIG. 2) at which the clamps 122 are adjacent a wall 124 of the housing 2 spaced a lateral distance from the derrick 110. The clamp 122, preferably a plurality of clamps for better maintaining the sometimes heavy pipe 118, are affixed to and extend laterally from the element 120 in order that the pipe can be moved the necessary lateral distance from the derrick 110. A power source 126, such as an electric motor and gear arrangement, is operably connected to the element 120 for moving the element between the first and second positions and for closing and for releasing the clamps 122 from a pipe 1 18 at said first and second positions.

The rotatable deck 90 can be equipped with rollers or conveying means known in the art for receiving the pipe 118 at the second position of the element 120 and moving said pipe to a pipe storage area 128.

Referring to FIG. 3, fluid processing and production equipment 34, such as for example, separators, water knockouts, shale shakers, and mud handling equipment, are preferably mounted on deck 74 in the housing chamber portion 80 and operably connected to the tank chamber portions, and the various production and drilling equipment as known in the art. Where additional space is needed, this equipment can be mounted on a rotatable deck, but in such cases the fluid conduits connected to the equipment become more difficult to maintain in an operable condition.

FIG. 4 shows the drilling equipment mounted on the rotatable deck 90 with the rig power source 130, and controls 132, as known in the art, mounted in the central portion of said deck 90. These controls can be any of the controls known in the art for operating any of the apparatus of the vessel. These controls can also be associated with TV cameras and other controls mounted on the helicopter deck 66 whereby many or all of the personal functions for operating the apparatus of this invention can be performed from a position spaced above the surface of the water 6.

FIG. 5 shows another embodiment of the drilling equipment 32 wherein a crown block 134 and associated equipment is mounted on a rotatable crown deck 108 that is associated with a crown deck 106. In this arrangement, a central opening 136 can be formed through the decks 106,108 for the passage of personnel and equipment to other housing chamberportions.

FIG. 7 shows yet another embodiment of the drilling equipment 32 whereby flexible pipe 138 is utilized in drilling, production,-and workover of the wells. I-Iere pipe delivery means 140, such as endless belts with grippers for example, moves the pipe 138 relative to the housing 2. The pipe is coiled in a bin 142 formed about the housing 2 by a guiding means 144 that runs on a track about the walls 124 of the housing 2. The flexible pipe 138 can also be stored in one of the tank chamber portions by providing guiding means for directing the pipe 138 thereto through, for example, one of the spoke connections 146 of the tank as shown in another embodiment in FIG. 3.

FIG. 6 shows another embodiment of the access conduit 60 wherein said conduit is formed of first and second telescoping conduit elements 148, 150. Power and gear means 152,154 is used for connecting the elements 148,150 one to the other and telescoping the first element 148 relative to the second element 150 between a first position at which the second end portion 156 of the first element 148 is spaced a preselected distance below the surface of the water, for example, about 30 feet to avoid wind and wave action, and a second position at which the second end portion 156 of the first element 148 is spaced at a preselected distance above the top surface 8 of the water 6. Sealing means 158, such as hydraulically operated sealing bladders, are positioned in the annulus formed between the first end portion 160 of the first element 148 and the second element 150. A buoy 162, containing actuating switches, is preferably operably attached to the power means 152 for initiating movement of the access conduit from the top surface 8 of a body of water 6.

It should be understood that the various equipment utilized in this invention can be positioned at other locations relative to one another without departing from the invention and other types of drilling and production equipment and controls can be utilized. Weighing material can also be carried in a portion of the tank chamber portions in order to minimize the stresses on the vessel.

In the operation of this apparatus, the vessel is towed to the desired location and then sunk by flooding the tanks and/or guying and pulling the vessel beneath the surface to the desired location in the body of water. Divers, for example, can then connect the vessel to the anchoring means for securing said vessel. The use of blowout preventers 102 sealing openings 18 thereafter provides for the conventiOnal drilling, completing, producing, and working over of well operations at a position removed from the violent weather conditions. Exhaust systems can also be associated with the housing 12, tank chamber and producing equipment for regulating the gases within the vessel.

Other modifications and alterations of this invention will become apparent to those skilled in the art from the foregoing discussion and accompanying drawing, and it should be understood that this invention is not to be unduly limited thereto.

What is claimed is:

l. A composite vessel for underwater drilling and production apparatus, comprising:

an elongated generally cylindrical housing having a chamber extending therethrougb, a longitudinal axis, and first and second end portions, said second end portion having a plurality of openings extending therethrough, each being substantially parallel to the axis and spaced about said axis an arcuate distance one from the other and a common radial distance therefrom;

a fluid tank having a chamber and a plurality of chamber portions, said tank and at least a portion of the chamber portions of the tank each circumscribing the outer periphery of the housing with said tank being spaced from said housing and maintained at a position along the axis of the housing preselected distances from the first and second end portions of the housing, said tank being attached to the housing with first and second attaching rings each having a first annular edge attached to the tank and a second annular edge attached to the housing with said rings being spaced one from the other forming a chamber between the tank and the housing;

a plurality of decks extending across the chamber of the housing substantially perpendicular to the axis of the housing and separating the housing chamber into a plurality of housing chamber portions, at least a portion of said decks having a plurality of openings extending therethrough with each opening being coaxially aligned relative to one of the openings through the second end portion of the housing;

a plurality of conduits each attached on one end to one of the tank chamber portions and on the other end to the chamber of the housing for selectively passing fluid between each of the tank chamber portions and the chamber of the housing;

anchoring means for maintaining the housing submerged within a body of water at a desired location relative to a subterranean formation at a position spaced preselected distances from top and bottom surfaces of the water and at a substantially vertical attitude with the first end portion of the housing being at a higher elevation than the second end portion of the housing; and

a conduit having a first end attached to the housing in communication with the chamber of the housing and a second end extending a distance above the surface of the water for movement of personnel and equipment between the chamber of the housing and a location above the top surface of the water.

2. A composite vessel, as set forth in claim 1, wherein all of the chamber portions of the tank circumscribe the outer periphery of the housing.

3. A composite vessel, as set forth in claim 1 wherein the chamber between the tank and the housing has a plurality of walls extending therethrough for dividing said chamber into a plurality of chamber portions.

4. A composite vessel, as set forth in claim 1, wherein the first and second end portions of the housing are of convex configuration and the housing is of a strength sufficient to withstand a liquid pressure of at least 50 p51.

5. A composite vessel, as set forth in claim 1, including fluid processing equipment mounted onone of the decks and attached to the conduit means for receiving fluid, processing said fluid, and separately delivering fluid to a tank chamber portion.

6. A composite vessel, as set forth in claim 1, wherein the conduit is formed of first and second telescoping conduit elements;

means for telescoping the first element relative to the second element between a first position at which the second end of the first element is spaced a preselected distance above the surface of the water and a second position at which the second end of the first element is spaced a preselected distance below the top surface of the water; and

means for sealing the annulus between the first and second conduit elements.

7. A composite vessel, as set forth in claim 1, including a helicopter landing deck attached to the second end of the conduit and an elevator associated with the second end of the conduit with said elevator being movable between a first position at which a platform of the elevator is adjacent the helicopter deck and a second position at which the platform is within the chamber of the housing.

8. A composite vessel, as set forth in claim 1, wherein at least one of the decks has an overlying rotatable deck movably connected thereto for rotation of said rotatable deck about the axis of the housing, said deck having an opening extending coaxially therethrough, coaxially alignable with the openings in the deck; and,

means for rotating the rotatable deck relative to its associated deck and maintaining the opening of the rotatable deck coaxially aligned with one of the openings in said deck.

9. A composite vessel, as set forth in claim 8, wherein a drilling rig derrick is fixedly attached to the rotatable deck about the opening of the rotatable deck for intermittently passing pipe from the derrick through each of the deck openings, each of the openings at the second end portion of the housing and against the earth at spaced-apart locations for drilling a plurality of wells beneath the housing.

10. A composite vessel, as set forth in claim 9, wherein the derrick has hoist cylinders and a vertically movable drilling head having an opening for releasably maintaining an end of a pipe, rotating the pipe and passing fluid into the pipe and moving the end of the pipe between a first position at which the pipe end is adjacent the rotatable deck and a second position at which the pipe end is spaced a vertical distance from the pipe.

11. A composite vessel, as set forth in claim 9, including an elongated pipe racking element having at least one pipe clamp extending laterally therefrom, said racking element being pivotally mounted adjacent the derrick for movement between a first position at which the clamp is in coaxial alignment with the opening of the rotatable deck and a second position at which the clamp is adjacent a wall of the housing spaced a lateral distance from the derrick andmeans for moving the pipe racking element between the first and second positions and attaching and releasing the clamps from a pipe at said first and second positions.

12. A composite vessel for underwater drilling and production apparatus, comprising:

an elongated generally cylindrical housing having a chamber extending therethrough, a longitudinal axis, and first and second end portions, said second end portion having a plurality of openings extending therethrough, each being substantially parallel to the axis and spaced about said axis an arcuate distance one from the other and a common radial distance therefrom; fluid tank having a chamber and a plurality of chamber portions, said tank and at least a portion of the chamber portions of the tank each circumscribing the outer periphery of the housing with said tank being spaced from said housing and maintained at a position along the axis of the housing preselected distances from the first and second end portions of the housing;

a plurality of decks extending across the chamber of the housing substantially perpendicular to the axis of the housin and separating thehousing chamber into a plur ity of housing chamber portions, at

least a portion of said decks-having a plurality of openings extending therethrough with each opening being coaxially aligned relative to one of the openings through the second end portion of the housing;

a plurality of conduits each attached on one end. to

one of the tank chamber portions and on'the other end to the chamber of the housing for selectively passing fluid between each of the tank chamber portions and the chamber of the housing;

anchoring means for maintaining the housing submerged within a body of water at a desired location relative to a subterranean formation at a-position spaced preselected distances from top and bottom surfaces of the water and at a substantially vertical attitude with the first end portion of the housing being at a. higher elevation than the second end portion of the housing; and

a conduit having a first end attached to the housing in communication with the chamber of the housing and a second end extending a distance above the surface of the water for movement of personnel andequipment between the chamber of the hous- 

1. A composite vessel for underwater drilling and production apparatus, comprising: an elongated generally cylindrical housing having a chamber extending therethrough, a longitudinal axis, and first and second end portions, said second end portion having a plurality of openings extending therethrough, each being substantially parallel to the axis and spaced about said axis an arcuate distance one from the other and a common radial distance therefrom; a fluid tank having a chamber and a plurality of chamber portions, said tank and at least a portion of the chamber portions of the tank each circumscribing the outer periphery of the housing with said tank being spaced from said housing and maintained at a position along the axis of the housing preselected distances from the first and second end portions of the housing, said tank being attached to the housing with first and second attaching rings each having a first annular edge attached to the tank and a second annular edge attached to the housing with said rings being spaced one from the other forming a chamber between the tank and the housing; a plurality of decks extending across the chamber of the housing substantially perpendicular to the axis of the housing and separating the housing chamber into a plurality of housing chamber portions, at least a portion of said decks having a plurality of openings extending therethrough with each opening being coaxially aligned relative to one of the openings through the second end portion of the housing; a plurality of conduits each attached on one end to one of the tank chamber portions and on the other end to the chamber of the housing for selectively passing fluid between each of the tank chamber portions and the chamber of the housing; anchoring means for maintaining the housing submerged within a body of water at a desired location relative to a subterranean formation at a position spaced preselected distances from top and bottom surfaces of the water and at a substantially vertical attitude with the first end portion of the housing being at a higher elevation than the second end portion of the housing; and a conduit having a first end attached to the housing in communication with the chamber of the housing and a second end extending a distance above the surface of the water for movement of personnel and equipment between the chamber of the housing and a location above the top surface of the water.
 2. A composite vessel, as set forth in claim 1, wherein all of the chamber portions of the tank circumscribe the outer periphery of the housing.
 3. A composite vessel, as set forth in claim 1, wherein the chamber between the tank and the housing has a plurality of walls extending therethrough for dividing said chamber into a plurality of chamber portions.
 4. A composite vessel, as set forth in claim 1, wherein the first and second end portions of the housing are of convex configuration and the housing is of a strength sufficient to withstand a liquid pressure of at least 50 psI.
 5. A composite vessel, as set forth in claim 1, including fluid processing equipment mounted on one of the decks and attached to the conduit means for receiving fluid, processing said fluid, and separately delivering fluid to a tank chamber portion.
 6. A composite vessel, as set forth in claim 1, wherein the conduit is formed of first and second telescoping conduit elements; means for telescoping the first element relative to the second element between a first position at which the second end of the first element is spaced a preselected distance above the surface of the water and a second position at which the second end of the first element is spaced a preselected distance below the top surface of the water; and means for sealing the annulus between the first and second conduit elements.
 7. A composite vessel, as set forth in claim 1, including a helicopter landing deck attached to the second end of the conduit and an elevator associated with the second end of the conduit with said elevator being movable between a first position at which a platform of the elevator is adjacent the helicopter deck and a second position at which the platform is within the chamber of the housing.
 8. A composite vessel, as set forth in claim 1, wherein at least one of the decks has an overlying rotatable deck movably connected thereto for rotation of said rotatable deck about the axis of the housing, said deck having an opening extending coaxially therethrough, coaxially alignable with the openings in the deck; and, means for rotating the rotatable deck relative to its associated deck and maintaining the opening of the rotatable deck coaxially aligned with one of the openings in said deck.
 9. A composite vessel, as set forth in claim 8, wherein a drilling rig derrick is fixedly attached to the rotatable deck about the opening of the rotatable deck for intermittently passing pipe from the derrick through each of the deck openings, each of the openings at the second end portion of the housing and against the earth at spaced-apart locations for drilling a plurality of wells beneath the housing.
 10. A composite vessel, as set forth in claim 9, wherein the derrick has hoist cylinders and a vertically movable drilling head having an opening for releasably maintaining an end of a pipe, rotating the pipe and passing fluid into the pipe and moving the end of the pipe between a first position at which the pipe end is adjacent the rotatable deck and a second position at which the pipe end is spaced a vertical distance from the pipe.
 11. A composite vessel, as set forth in claim 9, including an elongated pipe racking element having at least one pipe clamp extending laterally therefrom, said racking element being pivotally mounted adjacent the derrick for movement between a first position at which the clamp is in coaxial alignment with the opening of the rotatable deck and a second position at which the clamp is adjacent a wall of the housing spaced a lateral distance from the derrick and means for moving the pipe racking element between the first and second positions and attaching and releasing the clamps from a pipe at said first and second positions.
 12. A composite vessel for underwater drilling and production apparatus, comprising: an elongated generally cylindrical housing having a chamber extending therethrough, a longitudinal axis, and first and second end portions, said second end portion having a plurality of openings extending therethrough, each being substantially parallel to the axis and spaced about said axis an arcuate distance one from the other and a common radial distance therefrom; a fluid tank having a chamber and a plurality of chamber portions, said tank and at least a portion of the chamber portions of the tank each circumscribing the outer periphery of the housing with said tank being spaced from said housing and maintained at a position along the axis of the housing preselected distances from the first and second end portions of the housinG; a plurality of decks extending across the chamber of the housing substantially perpendicular to the axis of the housing and separating the housing chamber into a plurality of housing chamber portions, at least a portion of said decks having a plurality of openings extending therethrough with each opening being coaxially aligned relative to one of the openings through the second end portion of the housing; a plurality of conduits each attached on one end to one of the tank chamber portions and on the other end to the chamber of the housing for selectively passing fluid between each of the tank chamber portions and the chamber of the housing; anchoring means for maintaining the housing submerged within a body of water at a desired location relative to a subterranean formation at a position spaced preselected distances from top and bottom surfaces of the water and at a substantially vertical attitude with the first end portion of the housing being at a higher elevation than the second end portion of the housing; and a conduit having a first end attached to the housing in communication with the chamber of the housing and a second end extending a distance above the surface of the water for movement of personnel and equipment between the chamber of the housing and a location above the top surface of the water. 